Tone generating assembly for electronic piano



Aug. 16, 1960 TONE GENERATING ASSEMBLY FOR ELECTRONIC PIANO Filed June 9, 1955 4 Sheets$heet 1 IN V EN TOR.

. 7b Ck'fi0rd d4 fiizawwz 32 QZW/ Aug. 16, 1960 c. w. ANDERSEN TONE GENERATING ASSEMBLY FOR ELECTRONIC PIANO Filed June 9, 1955 4 Sheets-Sheet 2 INVENTOR. @ffawd I llll I Aug. 16, 1960 c. w. ANDERSEN TONE GENERATING ASSEMBLY FOR ELECTRONIC PIANO Filed June 9, 1955 1960 c. w. ANDERSEN 2,949,052

TONE GENERATING ASSEMBLY FOR ELECTRONIC PIANO Filed June 9, 1955 4 Sheets-Sheet 4 INVEN TOR.

any of the notes of the piano.

United States 2,949,052 Patented Aug. 16, 1960 ice TONE GENERATING ASSEMBLY FOR ELECTRONIC PIANO Clifford W. Andersen, De Kalb, Ill., assignor to The Rudolph Wurlitzer Company, North Tonawanda, N.Y., a corporation of Ohio Filed June 9, 19 55, Ser. No. 514,348

14 Claims. (Cl. 841.04)

This invention is concerned with the musical arts, and more particularly with an electronic piano. The pianoforte, or piano, as it is commonly termed, is an extremely popular instrument and is found throughout the world. In its conventional form, the piano is quite large and heavy. This makes it difficult to move conventional pianos, and it generally limits the use of pianos to first floor locations, and to the largest room in the house. This can be extremely undesirable from the standpoint of the student or casual pianist, and from the standpoint of other persons occupying the same residence.

Accordingly, it has been proposed that the size and weight of a piano be reduced by the provision of an electronic piano. It is known that a tuned reed having an electrical potential applied to it and vibrated near a conductive member will form with that member a variable capacity giving rise to an electrical oscillation which can be translated into a musical tone. I have found that when such a reed is percussively actuated, remarkably realistic piano tones can be produced if the various elements of the electronic piano are properly correlated, and the electrical oscillations generated are properly amplified and converted into audio oscillations. This invention is concerned with an electronic piano of this type.

I have found that the best results are obtained when the reeds and the associated pick up means are all mounted on a single rigid member or bar of high mass. I further have found that the natural or resonant frequency of this support or bar is of extreme importance.

Some of the notes corresponding to the various reeds often appear to be dead. In other words, there is no hangover to the notes. While most of the notes may sound with proper resonance, one or two notes may fail to have a proper duration. I have found that this is caused, in general, by damping of the reed vibrations of the dead notes by the reed bar or support. I further have found that many dead notes can be eliminated by providing a floating or resilient support for the reed bar.

Accordingly, it is an object of this invention to provide an electronic piano having a plurality of percussively actuated reeds mounted on a massive support wherein the support is resiliently or fioatingly mounted.

Measurement with an audio oscillator and an oscilloscope displays that dead notes occur at the resonant frequency of the bar. It may appear that the logical solution to the problem would be to provide a bar which would not have a natural frequency corresponding to Physical considerations preclude the possibility of producing a resonant bar having a resonant frequency above or below any of the tones of the piano, while practical production problems render it generally impossible to produce a bar which will resonate between any two notes of the piano. The only commercially practical way to produce the reed bars or supports is by casting. Unfortunately, some of the bars have blow holes or porous areas, and such blow holes or porous areas shift the resonant frequency of the bar, and the shift will not be uniform, but will depend on the extent of such blow holes or porous areas. Fortunately, however, it has been found that the resonant frequency of the bars stays within one or two notes on the scale. In many instances, the bars do not have any dead notes, but often they do.

Accordingly, it is an. object of this invention to provide means and methods for eliminating dead notes in an electronic piano.

More specifically, it is an object of this invention to provide means and methods for controlling or shifting the resonant frequency of a reed supporting bar for an electronic piano.

It is another object of this invention to provide means for tuning the reed supporting bar of an electronic piano by applying weights thereto at different locations.

Another object of this invention is to vary the physical dimensions of a reed supporting bar in an electronic piano for varying the resonant frequency thereof.

Another object of this invention is to control the resonant frequency of an electronic piano reed supporting bar by varying the number or position of reinforcing ribs.

A further object of this invention is to control the resonant frequency of an electronic piano reed supporting bar by forming the bar in two or more pieces made of one or more different types of metals and connected together to form a single bar.

Other and further objects and advantages of the present invention will be apparent from the following description when taken in connection with the accompanying drawings wherein:

Fig. 1 is a perspective view of an electronic piano, constructed in accordance with the principles of the invention;

Fig. 2 is a cross sectional view through the piano;

Fig. 3 is a perspective view of one end of the reed bar with associated reeds and pick ups in place thereon;

Fig. 4 is a top view of the reed bar assembly, including the reed bar, reeds, and pick ups;

Fig. 5 is a front view of the reed bar assembly;

Fig. 6 is a cross sectional view of the reed bar assembly taken substantially long the line 6-6 in Fig. 4;

Fig. 7 is another cross sectional View of the reed bar assembly taken substantially along the line 77 of Fig. 4;

Fig. 8 is a further cross sectional view of the reed bar assembly taken substantially along the line 88 of Fig. 4;

Fig. 9 is yet another cross sectional view of the reed bar assembly taken substantially along the line 99 of Fig 4;

Fig. 10 is a top view of the reed bar showing a modification thereof;

Fig. 11 is a fragmentary top view of the reed bar showing another modification thereof;

Fig. 12 is a cross sectional View taken along the line 1219. of Fig. 1 1;

Fig. 13 is a fragmentary top view generally similar to Fig. 11 showing a further modification of the reed bar;

Fig. 14 is a cross sectional view taken along the line 1-4-14 of Fig. 13;

Fig. 15 is a fragmentary top view similar to Figs. 11 and 13 showing a further modification of the reed bar and also showing a modification of the piano keys;

Fig. 16 is a longitudinal sectional view taken along the line 16-16 of Fig. 15;

Fig. 17 is an exploded perspective view of one end of the reed bar and support therefor;

Fig. 18 is a longitudinal sectional view taken substantially along the line 18--18 of Fig. 17;

Fig. 19 is a view similar to Fig. 18 showing a different type of support; and

Fig. is a view similar to Figs. 18 and 19 showing yet another type of support.

Referring now in greater particularity to the drawings, and first to Figs. 1 and 2, there will be seen an electronic piano 30 constructed in accordance with the principles of my invention. The piano includes a case 32 preferably formed of wood or plywood and having at the front thereof a keyboard 34 comprising a plurality of piano keys 36 corresponding to the keys of a conventional piano. The case also includes a fall board assembly 38 and a wire music rack 40 pivotally mounted thereon and capable of movement into position substantially against the keyboard 34 so that a fall cover (not shown) may be placed over the keyboard, fall board assembly, and music rack for transportation of the piano.

The piano case is mounted on four legs 42 which are detachably connected to the case, preferably by means such as threaded fastening means so that the legs may be removed for ready transportation of the piano. A foot pedal 44 for releasing the dampers is detachably connected to the piano by means of a flexible cable 46 of the type shown as a Bowden cable. The piano is provided with an electronic amplifier (not shown) mounted within the case 32 and connected to a loudspeaker 48 opening through suitable louvres (not shown) in the back of the case. Controls 50 are provided at the side of the case for the amplifier.

Further details on the foregoing may be found in my co-pending application Serial No. 495,113, filed March 18, 1955, and entitled Electronic Piano.

A bed 52 is mounted on the bottom. of the case on the inside thereof, and a balance rail 54 extends across this bed. The keys 36 of the keyboard 34 are pivotally mountedon the balance rail by means of the usual balance key pins 56 and felt pads or washers 58 surrounding these pins. The top surface of the balance rail is inclined as will be appreciated so as to support the keys in the inclined position shown in the drawings with the inner ends of the keys 36 resting on a felt pad 60 at the inner edge of the bed. At the outer or front end of the bed 52 there is provided a front rail 62 carrying a plurality of front key pins 64. A felt pad 66 is provided on the front rail at the outer edge thereof immediately beneath the outer ends of the keys 36. It will be appreci ated that the felt pad or strip 66 prevents the keys from pivoting about the felt washers usually provided about the outermost of the front key pins. Under such circumstances the keys would rise from the balance rail 54 in an undesirable manner.

A pair of wood blocks 68 is mounted at the opposite ends of the piano case 32 on the inside thereof, the blocks being appropriately screwed and glued in place. A reed bar assembly 70 is mounted on these blocks. The reed bar assembly includes a reed bar 72 of massive construction, preferably cast of gray iron. The exact construction of the reed bar assembly will be set forth later. For the present, it is suflicient to state that the reed bar is generally rectangular in configuration and supports a plurality of vibratile reeds 74 and associated pick up means 76. The reeds are electrically connected to the bar, while the pick up means 76 are insulated therefrom by an insulating strip or bar 78. An aluminum shield 80 is placed over the outer ends of the reeds and the pick up means to preclude hum in the output, and a felt pad 82 is interposed between the front edge of the reed bar and the shield 80 to prevent vibration of the shield.

The mounting of the reed bar will be referred to in more particularity hereafter, but for the present it may be noted that wood screws 84 are passed through suitable apertures in the bar, and passed through rubber washers 86 on top of fiber washers 88. The wood screws 84 are screwed into the wood blocks 68. At the bass end of the bar there are two wood screws 84, while at the treble end there is only on wood screw, since the treble 4 end is narrower than the bass end as hereinafter will appear.

A main rail 90 extends across the piano, being supported at its opposite ends by suitable blocks screwed and glued to the inside of the case. A plurality of whip flanges 92 is spaced along the bottom rear corner of the main rail, and a whip 94 is pivotally carried by each a of the whip flanges 92. Each whip is provided beneath its forward end with a felt pad 96, and a capstan screw 98 on the inner end of the corresponding key 36 engages beneath each felt 96. The capstan screws preferably are provided with square or other non-circular shanks for receiving a wrench to adjust the capstan screw up and down beneath the end ofthe whip.

A jack or fly 100 is pivotally mounted on each whip adjacent the felt pad 96. Each jack or fly 100 engages beneath a butt 102 of a corresponding hammer 104 having a felt pad or striker 106 on the end thereof. A plurality of butt flanges 108 is spaced along the main rail 90, and the butts 102 are pivoted thereon. Each butt is provided with a recessed portion 110, and with a jack engaging screw-112 which determines adjustably the time at which the jackor fly ceases to lift the butt and hammer. A butt spring 114 holds each hammer in lowered position as will be appreciated.

The hammers 194 are positioned to engage beneath the reeds 74 as will be appreciated. A damper lever 116 is positioned above each of the reeds except the top few at the treble end, and a damper 118 in the form of a felt pad is placed on each damper lever and engages 'a corresponding reed to damp the same. Each damper lever 116 is pivotally mounted on a damper lever flange 1 20, there being a plurality of such flanges positioned along the top rear edge of the main rail 90. A spring 122 associated with each damper lever holds the dampers in damping position. A damper lever wire 124 has its tail pivotally hooked through the inner end of each whip 94 as at 1'26 and has its upper end projecting through the rear end of the corresponding damper lever 116, a damper regulator button 127 being threaded on the upper end of each damper wire for adjusting the damper action.

It will be appreciated that each time a key is depressed the capstan screw 98 thereon pivots the whip in a counterclockwise direction as viewed in Fig. 2. This causes the jack or fly 100 to push up beneath the butt 102 and thereby to pivot the corresponding hammer 104 into percussive engagement with the corresponding reed 74 percussively to vibrate the reed. The last part of this motion is due to the inertia of the butt and hammer inasmuch as the screw 112 pushes the jack or fly 100 from jacking position at a predetermined location. Pivoting of the whip also pulls down on the corresponding damper wire 124 and pivots the corresponding damper lever 116 to retract the damper 118 from the reed that is to be engaged by the hammer, thereby freeing this reed for vibration and tone generation. It heretofore has been noted that some of the treble reeds do not have dampers. The vibrational time of such reeds is so short that dampers are unnecessary. However, dummy damper levers are provided which are terminated short of the reed bar 72 so that the feel of each key will be uniform.

A block 128 is mounted at each end of the main rail 90 and pivotally supports a damper release rod 130 for eccentric rotation about mounting'pins or rods 132. The

Bowden wire 46 connected'to the foot pedal 44 is connected by means (not shown) to the pin 132 at the treble end of the piano for eccentrically rotating the rod 130 to lift this rod against apad 134 onthe underside of each of the damper levers 116 whereby simultaneously to retract all of the dampers. Further details on the foregoing piano action can be found in my aforesaid application Serial No. 495,113.

Referring now to the details of construction of the reed bar assembly 70, in which connection reference should be had to Figs. 3-9, the assembly 70, as heretofore has been indicated, comprises a generally rectangular reed bar or support 72. The reed bar 72 includes a generally rectangular front rail 136 and a back rail 138. The front rail is connected to the back rail at the bass end by an integral side rail 140, and at the treble end by an integral side rail 142. The bar 72 is very nearly rectangular in outline, but is slightly wider at the bass than at the treble end. The back rail 138 is provided with a shelf 144 which is set down somewhat from the top of the rail 138, and which tapers from a maximum width at the bass end of the scale to a minimum width near the treble end. The frame is provided substantially at the midpoint between its ends with a reinforcing rib 146 integral with the front and back rails, and also has depending portions including feet 148 on the front bar, runners 150 on the back bar, and portions of the end bars 140 and 142 which extend below the level of the front and back bars. The feet 148 are used to position the bar for machining, and it is thought that desirable results in avoiding dead reeds could be obtained by grinding off or otherwise removing these feet, or by repositioning them. Similar efiects might be obtained by eliminating parts of the runners 150.

From a practical standpoint, the reed bar 72 preferably is cast, and then is machined to final dimensions. Satisfactory results have been obtained casting the bars of aluminum, or magnesium, or steel, or gray iron. Steel has been found to give the best results, but is expensive and relatively difiicult to machine, while gray iron has been found nearly as satisfactory as steel, and is much less expensive and is easier to machine. The rib 146 has been found not only to give mechanical rigidity to the bar, but also has been found helpful in eliminating dead notes.

The reeds 74, previously referred to, are made of steel, and are mounted along the back bar 138. The reeds vary in length, the bass reeds being the longest and the treble reeds being the shortest. All of the reeds include vibratile tongues 15?. and integral bases 154. The bases are thicker than the tongues, and a well defined internal shoulder 156 is formed between the bases and the tongues to determine the portion of the tongue that will vibrate. The bass reeds and some of the middle reeds as may be seen in Figs. 6 and 7 also are provided with weights 158 for lowering the frequency of vibration without making the reeds unduly large. These weights preferably are in the form of lead or the like which readily can be added to, as by adding lead in molten state, or can be subtracted from, as by filing, for properly tuning the reeds.

The reeds are mounted by means of cap screws 160 threaded into the back rail. Lock washers 162 are provided beneath the heads of the cap screws 160, and it will be appreciated that the washers preferably are made as units in the form of the well known Sems assemblies. Flat washers 164 are placed between the lock washers and the reed bases. The reeds thus are electrically connected to the reed bar, and project toward the front rail 136 as will be evident from the drawings.

The pick up means 76 is supported along the top of the front rail 136 by means of the insulating strip or bar 78 as previously has been indicated. The pick up means comprises three conductive sheets, preferably aluminum, identified by the numerals 166, 168 and 170 respectively. In the present instance the sheets are electrically interconnected by soldered lugs 172, and it will be understood that the three sheets could be one integral sheet. However, it is more convenient to manufacture the sheets as three separate parts, and furthermore the provision of three separate parts allows individual electrical polarization of the three sheets so as relatively to emphasize the notes of one part or another of the piano scale, such as the bass tones. Fingers 174 are struck up from the sheets 166, 168 and 170, except near the extreme treble end of the sheet 170, to form a comb-like configuration comprising rearwardly extending fingers 176 and alternate spaces 178. Near the upper end of the treble pick up sheet material simply is struck out to provide the alternate fingers 176 and spaces 178, no upwardly directed fingers being formed. The reeds 152 vibrate in these spaces 178 between the fingers 176, and the conductive sheets form with the reeds capacitors which vary in capacity in accordance with the vibrations of the reeds.

The reeds are mounted so as to be coplanar with the bottom surfaces of the pick up sheets, the three sheets being coplanar with one another. The amplitude of vibration of the reeds is such that they will vibrate below the pick up sheets, but will not progress above the tops of the struck up fingers 174. In the case of the upper treble reeds, it will be understood that the amplitude of vibration is sufiiciently small that the reeds will not pass above the top surface of the sheet 170, and hence no upwardly struck fingers 174 are necessary. It will be apparent from Fig. 4, and also from Figs. 6, 7 and 8 that the narrowing of the shelf 144 progressively places the reed bases closer to the pick up means 76 as is necessitated by the varying lengths of the reeds.

The pick up sheets are mounted by means of cap screws 18% preferably having lock washers 182 preassembled therewith in the form of the well known Sems fastening unit. A flat steel washer 184 is placed beneath each lock washer 182. Preferably there are five cap screws for each of the plates 166, 168 and 170. The first and fifth of these cap screws has a fiber bushing 186 (Fig. 6) extending through the pick up sheets and also through the insulating strip or bar 78 into contact with the front rail 136, electrically toisolate the pick up sheets from the bar 72. Fiber washers 188 (Figs. 7-9) are placed beneath the washers 182 associated with the remaining cap screws 18% to insulate the cap screws from the pick up sheets, and hence to insulate the pick up sheets from the bar 72. It will be appreciated that the two bushings serve to position the pick up sheets relative to the cap screws 180, and that the fiber washers are all that are necessary to insulate the remaining cap screws from the pick up sheets, since the pick up sheets are positioned away from these screws by the two bushings per sheet.

Reference previously has been made to the means for supporting the bar assembly 72 with reference to Fig. 3. The showing in Fig. 3 is of the bass end of the bar assembly, and the treble end may be seen in Figs. 17 and 18. The construction at the treble end is the same as at the bass end, a block 68 being screwed and glued in place on the inside of the end of the piano case 32, and a rubber washer 86 on top of a fiber washer 88 being interposed between the bar and the block 68. Due to the decreased width of the treble end, only one screw 84 and associated rubber and fiber washer is provided, whereas two are provided at the bass end. However, except for the number, there is no difference between the mounting at the treble and bass ends. It will be appreciated that the bar is clamped against the Washers only tightly enough to hold the bar in place, and not tightly enough to compress the rubber washers tightly. Thus, problems of acoustical feed back are substantially eliminated, and dead notes are minimized.

As heretofore has been noted, one or more of the notes may be dead due to resonance of the bar at the frequency of the reed. The notes which have been found primarily to be dead are Gt, Ait, C, Cit, or D at two octaves above middle C. I have found that these dead notes can be eliminated by the addition of one or more weights of proper configuration and disposition. Since these weights make the previously dead notes ring properly,- the weights hereinafter will be referred to as ringers.

Each ringer 190, see Figs. 3, 4, 7 and 9, comprises a rectangular block of metal having a bore 192 therein of sufiicient diameter to receive one of the 'bolts or screws 160 or 180, and 'havinga counterbore 194 to receive the corresponding bolt head. The blocks are rectangular as heretofore has been indicated, 'and'the bores 192 and counterbores 1% are positioned midway from end to end thereof, but are positioned closer to one of the long parts than to the other, the bores thus being eccentric relative to the blocks. These blocks preferably are made of steel, and the ringers that are mounted toward the bass end of the piano preferably are mounted on the front rail 136, directly beneath the lock washer 182 of the bolt 18% and on top of the fiber Washer 183 or the bushing 186. The ringers 190 that are mounted toward the treble end are mounted by means of the bolts 160 which secure the reeds in place, and spacers 196 are positioned beneath the ringers to space the ringers above the reeds. The principal reason for providing these spacers, which like the ringers preferably are made of steel, and which are cylindrical in nature, is to space the ringers above the heads of the adjacent bolts or Sems units.

Sometimes a reed bar will have no dead notes associated with it. When a reed bar does have a dead note, however, one of the ringers 1% is placed on the fourth bolt 180 from the bass end of the reed bar, and a ringer is tried on the sixth reed from the extreme treble end of the reed bar. Occasionally it will be necessary to move either or both of these ringers, one bolt or one reed, or sometimes more in one direction or another, and excellent results often can be obtained by rotating a ringer through forty-five or ninety degrees.

Usually the ringer which is tentatively positioned on the fourth boit 18f on the bass end of the bar corrects dead notes in Gt or Ali, nearly two octaves above middle C, while a ringer placed on the sixth reed from the top will correct the dead notes of C, Cit or D at two octaves above middle C. Sometimes, with a ringer mounted parallel to the bar, C will be dead, and Cit will be all right. When the ringer is rotated through ninety degrees,

the C note will be satisfactory, but the Cit will be dead. Rotation of the ringer to a forty-five degree position then adjusts the resonant frequency of the bar midway between the C and Ct, and satisfactory results are ob tained, neither of the notes at this time being dead.

Positioning of the ringers as noted above generally will cause all of the notes to ring properly. Occasionally, however, it may be necessary to provide a third ringer, and this generally is done adjacent to the ringer on the sixth reed from the top. Occasionally, it will be found desirable to place one of these ringers parallel to the length of the bar, with the other at a ninety degree angle thereto. In general, placement of the ringers at the present time is empirical. The ringers change the resonant frequency of the bar, or at least lower the Q thereof so that the resonance is broadened and has a lowered peak. It is thought that perhaps the position of the ringer or ringers relatitve to an antinode of a standing wave in the bar is important, but the precise relationship has not as yet been determined.

In view of the success of the ringers in eliminating dead notes, it is thought that perhaps one or more pieces of steel could be secured to the rear or back. portion of the bar near the treble end to eliminate many dead notes. Also, it has been found that merely resting a weight on top of the bar near the treble end thereof will correct many dead notes, but this of course is not commercially practicable since the bar would fall off the first time the piano: was moved.

Excellent results also have been obtained by screwing heavy weights into the treble end of the bar, but the ringers are the simplest expedient known at present, and are also the most satisfactory.

A modification of the invention is shown in Fig. 10. In this embodiment of the invention the parts heretofore shown and described are identified by similar numerals with the addition of the suflix a. The reed bar 72a --is generallysimilar to that previously-described, having a front rail 136a and a back rail 138a interconnected by end rails or pieces 140a and 142a. The difierence is that instead of the single central rib 146a, there are provided five ribs 146a. Besides providing a more rigid structure, these ribs help in many instances to avoid dead notes, although it has been found that the reed bar of Fig. 10 is not absolutely perfect in this respect, and may require the addition of one or more ringers for perfect results. Generally speaking, however, the reed bar of Fig. '10 presents improved results over the form of the reed bar previously shown and described.

A further embodiment of the invention is shown in Figs. 11 and 12. This embodiment of the invention partakes of some of the characteristics heretofore shown and described, and similar parts are identified by similar numerals with the addition of the suffix b. A reed bar 72b in this instance is provided with no integral ribs.

Instead, the front rail 13612 and the back rail 13 8b are provided with a series of aligned bores 196 countersunk at 198. Bolts or screws 200 project through these bores,

having their heads in the countersinlts, and are threaded into the ends of one or more movable ribs 14611. One or more ribs thus can be moved about until a position is found at which there are no dead notes. It will be understood that the taper of the bar makes it possible for a single rib to fit perfectly at only one position, but a single rib will fit approximately at a plurality of positions, and steel washers can be used as shims to make a single rib fit at any one of several positions. Good results in eliminating dead notes have been obtained in this manner, but considerable extra effort is entailed over the use of the ringers heretofore shown and described in that the front and back rails of the bar must be drilled for the bolts or screws 2%, and the ends of the ribs must be drilled and tapped.

A further embodiment of the invention having considerable merit in eliminating dead notes is shown in Figs. 13 and 14. In this instance the bar is made of two sections of different metals. Similar parts shown in these two figures are identified by similar numerals with the addition of the suffix c. The bar 720 comprises two sections split approximately at A just short of two octaves above middle C. The front rail 1 36c comprises a lower section 206 and an upper section 208, while the back rail 138a comprises a lower section 202 and an upper section 2%. A rib section 210 is cast integral with the lower sections 202 and 2%, and a rib section 212 is cast integral with the upper rail sections 204 and 208. Preferably, the lower rail sections 202 and 206 and the associated rib section 210 are cast of aluminum, while the upper rail sections 204 and 208 and the associated rib section 212 are cast of steel. The mating surfaces of the rail sections are machined flat, and bolts 214 are passed through one of the rib sections, for instance the upper crib section 212, and are threaded into the lower rib section to hold the bar sections tightly together, the two rib sections 210 and 212 thus effectively forming a single rib 146s. The smaller bar portions thus produced have substantially higher resonant frequencies, and even though the two parts are tightly clamped together, the bar does not resonate substantially as a unit so as to provide any dead notes. The tuning of the reed bar by forming it in sections is believed to be an expedient that will completely eliminate dead notes, thereby avoiding the necessity of tuning the bar after assembly of the reeds and pick ups therewith.

A further embodiment of the split bar is shown at 70b in Figs. 15 and 16, similar parts again being identified by the use of similar numerals, this time with the addition of the suflix d. In this instance, the back rail is cast in two pieces 202d and 204d, while the front rail is cast in a lower section 206d and an upper section 208d.

-embodiment of the mounting is shown in Fig. 19.

Again the lower section of the reed bar preferably is cast of aluminum, while the upper section is cast of steel. The bar sections are joined by lap joints 216. These lap joints may be formed by an overlying tongue or shelf 218 on the lower bar sections, as the section 206d of the front rail 136d, and by a generally complementary lower tongue or shelf 220 on the upper bar sections, as the section 208d of the front rail. A screw or bolt 222 passes through one of the shelves 218 and 220, for example the latter, and is threaded into the other.

It will be appreciated that the fastening means used for holding the bar sections together in accordance with the embodiments of either Figs. 13 and 14 or Figs. 15 and 16 may prevent spacing the reeds as closely at the junction as at other positions. Other fastening means which would be functionally equivalent to those shown also might have this same characteristic. Accordingly, it might be impossible to space all of the tone generators and all of the corresponding keys 36 uniformly, at least at the inner ends of the keys, whereas it will be apparent that the outer ends of the keys which are engaged by the fingers must be spaced uniformly in accordance with conventional practice. In this event, and as is illustrated in Fig. 15, the keys 36d would be provided with intermediate angularly disposed portions 226 whereby the outer ends of the keys would be spaced in accordance with conventional practice and the inner ends 228 would be spaced to correspond to the associated reeds 74d. This would require a special key construction for each of several keys, and hence it is to be avoided if it is at all possible to do so.

Reference heretofore has been made to mounting the bar by means of the block 68 screwed and glued to the inside of the piano case 32. A further modification or In this figure the case 32 and block 68 remain as previously described, while the bar 70 also is substantially without modification, the same numerals therefore being used. The difference resides in the specific mounting means. Rather than the wood screw and the rubber washer on top of the fiber Washer, the mounting means in Fig. 19 comprises a cylindrical rubber block 230 having the rather shallow fiat heads 232 of a pair of oppositely directed threaded studs 234 molded therein. One of the studs. 234 is threaded directly into the block 68 while the other stud projects upwardly through a suitable aperture in the bar 70 and has a nut 236 threaded thereon to hold the bar in place. This mounting structure has been found to be slightly less desirable than that previously described in that the mounting is so yieldable that the bar moves about undesirably when the piano is carried. The mounting means of Fig. 19 also is slightly more expensive than that perviously described. However, it will be understood that the mounting means of Fig. 19 is quite serviceable and that one block 230 and associated studs preferably would be placed at the treble end of the bar, and two such blocks and associated studs at the bass end.

A further embodiment of the mounting means is shown in Fig. 20 and partakes of some of the characteristics of both of the mounting means heretofore described. An elongated threaded stud 238 is threaded into the top of the block 68, and a jam nut 240 is threaded thereon tightly against the top of the block to hold the stud 238 in fixed position. A height determining nut 242 is threaded on the stud and is spaced above the jam nut 240'. A rubber Washer 244 is placed on the stud above the height determining nut 242, and the bar 72 rests on the rubber washer 244, the stud 238 extending up through a suitable aperture in the bar 72 and having a nut 246 threaded thereon to hold the bar in place. The mounting means shown in Fig. 20 is better than either of those previously described in that the height of the reed bar can be adjusted. It is better than the embodiment shown in Fig. 19 in that the mounting is not too yieldable, but

it is somewhat more expensive and more difficult to use than the first described mounting means, as in Figs. 17 and 18.

The reed bar constructions and mounting means heretofore shown and described are successful in eliminating dead notes. The resilient mounting means for the bars serve to prevent acoustical feed back to the bars, and furthermore it has been found that when the bars are clamped rigidly to the case that there are more dead notes than when the bar is provided with a floating suspension. The tuning of the reed bar by means of the ringers, or by variation in number or position of the reeds, or by sectionalization of the reed bar either changes the resonant frequency of the reed bar or broadens the resonance thereof so that dead notes are eliminated. It will be appreciated that ringers of different shapes than those specifically shown and described could be used, that bars having ribs of greater or lesser number could be provided, and that the sectional bars could be made of three or more pieces, rather than the two shown and described. In short, it will be understood that the specific embodiments of the invention herein shown and described are for illustrative purposes only.

Various changes in structure will no doubt occur to those skilled in the art, and are to be understood as forming a part of my invention insofar as they fall within the spirit and scope of the appended claims.

The invention is claimed as follows:

1. A tone bar assembly for an electronic musical instrument comprising a massive support of open, generally rectangular outline including relatively long front and rear members rigidly interconnected by relatively short side members, a plurality of vibratile tone generators of dilferent frequencies mounted directly on one of said relatively long members and extending toward the other, pick up means mounted on the other of said relatively "long members and cooperable with said tone generators,

and means rigidly mounted on said support over a distance longitudinally thereof greater than the spacing between adjacent tone generators to avoid resonance of said support at any of the frequencies of said tone generators.

2. A tone bar assembly as set forth in claim 1 wherein the means to avoid resonance of said support comprises Weight means rigidly mounted on said support on at least one of the long members thereof.

3. A tone bar assembly as set forth in claim 1 wherein the means to avoid resonance comprises rib means inter mediate said short side members and rigidly interconnecting said relatively long front and rear members.

4. A tone bar assembly as set forth in claim 3 wherein the rib means comprise a movable rib and means for rigidly joining said rib to said relatively long front and rear members.

5. A tone bar assembly as set forth in claim 1 wherein the support is made in a plurality of sections comprising a like plurality of sections of said relatively long front and rear members, and wherein the means to avoid resonance of said support comprises means for rigidly joining said support sections together, said support sections being made of different materials.

6. A tone bar assembly for an electronic musical instrument comprising a massive support of generally rectangular outline including relatively long front and rear members rigidly interconnected by relatively short side members, a plurality of vibratile tone generators of different frequencies mounted directly on one of said relatively long members in spaced side-by-side relation transverse of said member and extending toward the other long member, pick up means mounted on the other of said relatively long members and cooperable with said tone generators, eccentric weight means rigid with said support, and stud means clamping said weight means on said support with said weight means movable along said support and eccentrically rotatable for tuning said sup- 1 1 port to avoid resonance thereof at any of the frequencies of said tone generators.

7; -A tone generating assembly for a musical instrument comprising a massive support including an elongated member, a plurality of vibratile tone generators of different frequencies spaced along and mounted directly on said elongated member transverse of said elongated member and projecting therefrom, and a plurality of eccentric Weights mounted directly on said support, and a plurality of studs respectively mounting said weights on said support with said weights movable linearly'thereon and eccentrically rotatable for tuning said support to avoid resonance thereof at any of the frequencies of said tone generators.

8. A tone generatingassembly for an electronic musical instrument comprising a massive support of generally rectangular outline including relatively long front and rear members rigidly interconnected by relatively short side members, a plurality of vibratile tone generators of different frequencies mounted along and directly on one of said relatively long members by a plurality of fastening members in spaced apart parallel side-by-side relation projecting toward the other long member, pick up means mounted on the other of said relatively long members by a plurality of fastening members and electrically cooperable with said tone generators for generating electric oscillations corresponding to musical tones, and a plurality of eccentric weights rigidly mounted on said support by some of said fastening members, said weights being shiftable fromone fastening member to another and being eccentrically rotatable about said fastening members.

9. A tone assembly as set forth in claim 8 wherein the fastening members comprise bolts threaded into said support, and wherein said bolts pass through said weights, and wherein some of said Weights have spacers positioned between them and said support.

10. A tone generating assembly for an electronic musical instrument comprising a rigid massive support of open, generally rectangular outline including relatively long front and rear members rigidly interconnected by relatively short side members, a plurality of vibratile tone generators of different frequencies mounted directly on one of said relatively long members and extending toward the other, pick up means mounted on the other of said relatively long members and electrically cooperable with said tone generators to produce electric oscillations,

means rigidly fixed on said support and disposed longitudinally thereof over a distance greater than the space between adjacent tone generators to avoid resonance of said support at any of the frequencies of said tone generators, and means floatingly supporting said support.

ll. A tone generating assembly as set forth in claim 10 wherein the means for floatingly supporting the support comprises -a block, means interposed between said :block and said support including .a resilient washer, vsand :a threaded fastener passing through said support and washer and into said block.

12. A tone generating assembly as set forth in claim 10 whereinthe means for fioatinglyvsupporting'thesmassive support comprises .a resilient block havinga plurality of threaded fasteners molded therein and extendingfinopposite dire .ions therefrom, oneof said threaded fasteners extending into said support.

13. A tone generatingassemblyas set'forth in.claim.10 wherein the means for floatingly supporting the.rnassive support comprises a threaded stud, a nut .adjustably threaded on said stud, a resilient washer supported on said nut, said stud extending through said massive support with said massive support resting on said resilient washer, and a nut on said threaded stud holding said massive support down in such position.

14. A tone generating assembly for an electronicmusical instrument comprising a massive integral cast metal support of generally rectangular outline including relatively long front and rear members rigidly interconnected by relatively short side members integral therewith, a plurality of vibratile tone generators of different frequencies mounted directly on and in electrical contact with one of said relatively long members in spaced apart parallel side-by-side relation extending toward the other long member, insulating means on the other of said long members, pickup means mounted on said insulating means and in capacitive relation to said vibratile tone generators, and weight means rigidly secured to and engaged said support over a distance longitudinally of the support greater than the space between adjacent tone generators to prevent resonance of said support at any of the frequencies of said tone generators.

References Cited in the'file of this patent UNITED STATES PATENTS 

